Nonlinear Rigid–Flexible Multibody Modeling of Arching Masonry Walls Subjected to Blast Loading

Abstract

The blast response of arching masonry walls is a challenging and complex structural mechanism that involves a range of physical phenomena, such as rocking, cracking, unloading and reloading effects, dynamic variation of the reactions, and time-dependent stability characteristics. The evolution of longitudinal and lateral inertial forces results in a coupled in-plane/out-of-plane dynamic response that, in turn, affects the arching mechanism and its stabilizing/destabilizing effect. This paper studies the blast response of realistically supported walls in which the elongation of the wall is restrained by the supporting structural elements. The study explores the dynamic development of the arching action in such walls and the evolution of a time-dependent thrust force. The latter affects almost any aspect of the wall response: in-plane and out-of-plane coupling, evolution of longitudinal stress waves, and global strength and stability. To address this challenge, a rigid–flexible multibody model for the nonlinear-dynamic analysis of one-way arching walls subjected to blast loads is developed. The nonlinear model takes into consideration the aforementioned physical aspects and aims at minimizing the required computational time. Based on the principle of virtual work, the model considers dynamic equilibrium conditions, cracking processes, geometrically nonlinear kinematics, dynamic contact at the interfaces, and nonlinear constitutive behavior of the mortar material. This spectrum of features is compiled into a unified specially tailored finite-element formulation. The masonry units are modeled as rigid bodies, whereas the mortar joints are modeled as inelastic nonlinear flexural members. The study is accompanied by a series of analyses and comparison with existing models and experiments that altogether validate the model and quantitatively explore the critical aspects of the physical behavior.